Silver won't affect the werewolf. It hunts humans exclusively; put it between a panther and a human and it will choose the human every time unless provoked by the animal. In that case, it will kill the animal and then kill the human.
They're intensely strong and can take a lot of damage before going down. Sometimes your only option will be to kill the wolf, as getting close enough to contain it drastically increases your risk of being bitten.
An attack from a werewolf will kill most Muggles and almost all wizards if the wounds are bad enough or left untreated. Powdered silver and dittany will seal a werewolf bite, but it won't cure the infection once it starts. Scars from these bites and scratches don't easily fade.
The condition can be passed even when one isn't transformed — should my saliva mix with your blood, you may experience minor symptoms (a fondness for undercooked meat, a heightened sense of smell, irritability) even if you never transform.
The person affected by this remembers killing those people, but they couldn't control themselves.